Contact plug assembly



July 8, 1941. w. P. HERMAN CONTACT PLUG ASSEMBLY Filed Feb. 2, 1938 Z Sheets-Sheetl INVENTO mZ/MM ATTORNEY July 8, 1941. w, P, HERMAN 2,248,082

' CONTACT PLUG ASSEMBLY Filed Feb. 2, 1938 2 Sheets-Sheet 2 ji u 12 .12 ,z 1 .13 j/; .141 12 .15

INVENTOR BY W/M 14k ATTORNEY ?atentedf July 8, 1941 UNITED STATES PATENT orric CONTACT PLUG ASSEMBLY William P. Herman, Providence, R. 1. Application February 2, 1938, Serial No. 188,262

2 Claims.

'My' present invention relates to the manufacture of electrical contact plugs and has particular reference to a novel construction of contact blades and novel methods of assembly of the contact blade with the electric cord.

It is the principal object of my invention to provide a contact blade which is firmly attached to the cord lead wire against abnormal pulls and which provides additional anchorage for the blade in the socket. 4

It is an additional object of my invention to provide frictional engagement means on the contact blade which are universally applicable to all the standard types of electric plug sockets or receptacles.

Another object of my invention is to provide various methods which will facilitate the securing of cord lead wire to the contact blade. 1

which are easy and economical to practice, and which will facilitate assembly of the final plug.

With the above and other advantageous features in view. my invention consist-s of novel methods of manufacture and assembly, and a novel arrangement of parts more fully disclosed in the detailed description following, in conjunction with the accompanying drawings, and more specifically defined in hereto.

In the drawings, a

Fig. 1 is a perspective view of a completely assembled plug with the contact blades of the present invention;

Fig. 2 is a plan view of a contact blade of the present invention with the cord lead wire attached thereto; I

Fig. 3 is a vertical section taken along lin 3-3 of Fig. 2;

Fig. 4 is another vertical section taken along line |--l of Fig. 2; v

Fig. 5 is a sectional view of an electric socket with the contact plug of the present invention inserted therein, one side of said plug being broken away; a

Fig. 6 is a diagrammatic view of a contact blade of the present invention in contact with one form of plug socket en agement means:

Fig. 'l is a similar view with another form of plug socket engagement means;

Fig. 8 is a similar view with another form of plug socket engagement means;

Fig. 9 is a similar view, the plug socket being of the T-shaped type;

Fig. 10 is a side elevation of the T-shaped formation shown in Fig. 9;

the claims appended Figs. 11 and 12 are perspective views of modifled forms of contact blades;

Fig. 13 is a plan view of a multiple strand cord lead wire with the end stripped;

Fig. 14 is an' edge view of a blade with the cord lead wire inserted therein preparatory to soldering;

Fig. 15 is a perspective view of the blade and cord soldered and ready for assembly;

Fig. 16, is a; diagrammatic view of the working layout for soldering;

Fig. 17 is a plan view of a contact blade with the'cord lead wire superimposed thereon ready for spot welding;

Fig. 18 is a similar view showing the cord spot welded to the blade;

Fig. 19 is a plan view showing the spot welded cord inserted into the slot and partially twisted;

Fig. 20 is a plan view of the spot welded cord and blade ready for assembly, and

Fig. 21 is a perspective view partially diagrammatic showing the vspot welding method and apparatus.

Referring more in detail to the drawings illustrating my invention, numeral l0 generally designates a standard plug body made of either hard or resilient rubber, Bakelite," or any other suitable material. The plug body I!) has two spaced contact blades ll protruding in a conventional manner from one end, and a cord lead wire I2 extending to the opposite end. The contact blade "is preferably of the selfanchoring type, having a rectangular elongated contact portion I3 tapered at the end as at It, a relatively narrow portion I5 adapted to engage abutting shoulders oi. the contact plug 7 body and a rectangular end portion I6 having will engage every type of standard receptacleconstruction as will be hereinafter a transverse slot I'I' into which the cord lead wire i2 is anchored. Instead of the narrow portion l5 and abutting shoulders, other self-anchoring means such as struck plugs may be used. I provide the contact portion I3 of the blade II with a plurality of detents or pips protruding from both sides thereof. The detents are carefully spaced and arranged so that they more fully described.

The detent I8 is placed adjacent the tapered end ll of the contact blade and centrally located between the tip of the blade and the standard opening IS in the blade. On the other side of the openinglil, approximately /3 along the contact portion of the blade from the ta- .pered end thereof are a pair of spaced detents 20. The detents 20 are on the opposite of the blade from the detent l3. Spaced from the detents 23 is a detent 2| approximately the same distance from the detents 20 and from the detent l8. The detent 2| is on the same side of the blade as the detent I 3 and in vertical align-' ment therewith. The contact blade II is so anchored in the plug body I thatthe single detents I8 and 2| face outwardly and the pair of detents :0 face inwardly.

Referring specifically to Fig. 5 of the drawand that the hereinafter described methods be used. a In soldering the cord lead wire l2 to a contact blade 28 theend of the wire is stripped of its inings, the plug receptacle22 has the conventional contact blade receiving slots 23; an abutting shoulder portion 24 between the slots and armate spring contact members 25 placed to extend in the path of the inserted contact blade. When the contact blade is inserted into the slot of this contact.

Figs. 6, 7 and. 8 diagrammatically show the action of the contact blade with various standard forms of .plug receptacle contact spring members. In each instance, one or more of the detents are brought into such contact with the spring members 23a, 25b, 25c, 25d and 23c, that there will be a releasable lock to the removal of the contact blade from the receptacle. Figs. 9 and 10 illustrate the action in a standard form of receptacle with a T-shaped slot.

The contact blades may also be constructed 1 to accomplish the desired result by using outwardly extended lugs 23 as in Fig. 11, which are placed in the same position as the detents I3, and 2|. A plurality of detents may be put in the lower and ;upper portion of the contact blade instead oLthe single detents l3 and 2|. Another form of blade such as shown in Fig. 12 may be used in conjunction with the detents,

out portion 21 of the opening l9 in the form of a struck up lug to accomplish the same purpose.

Referring to the standard forms of plug receptacle with the various types of contact spring members illustrated in Figs. '5 to 10 inclusive, it is obvious 'that the spacing of the detents is of j the utmost importance if the desired result is to be accomplished.

As illustrated in applicants copending application Serial N'o. 99,848; filed September 8, 1936 and entitled Connector plug assembly apparaspot welded by the methods hereinafter de- 3 scribed.

It is obvious that the hereinafter described methods, may be used with any type of contact 1 blade, either wither without detents or lugs.

However, to ensure a connection which will withstand much more than the minimum amount of pull required by the Underwriters Laboratories, it is desirable that the blades be slotted, as at ll,

'similar material.

suiation for about of an inch. The bare end of the wire is slipped into the slot 29, the wire lying flat in parallel relation to the contact blade 28 while the bare end is manually pressed against the blade and turned upwardly (see Fig. 14) the wire being held in such a position that the end will not extend beyond the end of the contact blade. The method of soldering is facilitated by thearrangement shown in Fig. 16, a stove 30 being placed upon the work table and containing three shallow trays numbered 3|, 32 and 33; trays 3| and 33 are preferably made of metal and tray 32 is preferably made of glass or hands of the assembler or operator; this amounts to a preheat which will facilitate the subsequent steps of the process The cord lead wire I2 is slipped into the slot 29 ina manner I hereinbefore described (see Fig. 14), and the cord end and blade end are now dipped into the tray 32 which contains the soldering solution,

which may be any standard type, but a preferred it is extremely important that the soldering be j confined to the very tip of the blade; the soldering solution should therefore be kept at a depth no greater than A of an inch. The blade end and cord end are immediately dipped into the tray 33 which contains the solder mixture com- 1 this form including the retention of the cutprising approximately65 parts of tin to 35 parts of lead, which mixture should also have a depth no greater than AM of an inch. The cord and blade are now immediately dipped into a fourth glass tray 34 containing a cooling, neutralizing solution comprising approximately 50% commercial ammonia and 50% water.

Referring more particularly to Figs. 14 and 15, v

the contact blade 28 is now pulled back in a vertical plane with the cord lead wire until the wire and blade assume the position in Fig. 15, this tumlng actionof the blade twisting the multiple strand wire and tending to take up any slack in the strands and ensure perfect-electric conductivity. The blade and cord are nowready for assembly in the plug.

If it be desirable or preferable to spot weld the wire to the blade, insteadof soldering, that can be done as follows? The cord lead wire 12 is superimposed upon metallic rectangular block 38. The block 38 has two rectangular cut-out portions 39 at 'one end thereof, leaving a relatively narrow raised portion 40 which corresponds in width to the width of the lower edge of the contact blade 35 after it is cut out, the block 33 also having a suitable Tray 3| normally contains the contact blades which are heated to as high a a temperature as is possible without scorching the electric cord connection to one arm of an electric circuit. 'Ifhe spot weldingis done by a metal rod 4i having two dielectric guiding posts 42 oppositely disposed on said rod; the posts 42 have diverging portions 43 at the bottom portions thereof which straddle the upwardly raised portion 40 of the block 38. The rod 4! is connected in suitable manner with the other arm of the electrical circuit, and the contact blade and wire, arranged as in Fig. 17, are placed across the block 38 with the slotted portion of the contact blade and the fan shaped bare end of theconrtact wire extending across the upward raised portion 40 of the block. The rod 4| is brought down upon the blade so that the bottom ends of the insulated portions 42 or the rod 4| will ride into the cut-out portion 39 in the block ll. The sloping'sides 43 oi the insulated portions tuck any loose ends of wire under the weld and the wire becomes completely spot welded to the contact blade below the slot, as at 44, see Fig. 18. The cord lead wire is then swun through the slot and the contact blade is turned, as in Fig. 19, into the position shown in Fig. 20 to give the multiple strand wire the desired twist.

While I have described specific constructional embodiments oi the invention, and specific meth-' ods for assembly, it is obvious that these are merely illustrative, and that changes in=--the size and shape of the parts, in their relative arrangement, and in the methods followed, may be made to suit the requirements for diiierent plug designs, without departing from the spirit and'the scope of the invention as defined in the appended claims.

I claim:

, tending from the inner face intermediate the ends thereof, and a projection extending from the outer face adjacent the upper end thereof, said projections bei r g positioned to permit at least one of them to pass beyond the effective contacting area of a spring contact member, whereby passage of said projection permits movement of said spring member to yieldingly interpose itself into the path of return movement I or said projection.

2. A contact blade for a contact plus, comprising a fiat rigid blade of generally rectangular form, said blade having a centrally positioned end projection extending from one face thereof, a pair of aligned spaced projections spaced from said end projection and extending from the opposite face thereof, and an additional centrally positioned projection spaced beyond said aligned projections and extending from the same face as said first named centrally positioned projection.

WIILIAM P. 

